| 摘要 |
PROBLEM TO BE SOLVED: To avoid the uncontrollable state of a motor by a method in which an OFF-time limiter which outputs a 2nd operation command by which the OFF state with a minimum OFF-time is kept is provided. SOLUTION: A 1st operation instruction command A which is the output of an operation command generating means 1 and a minimum OFF-time Δt are inputted to an OFF-time limiter 4 and the OFF-time limiter 4 outputs a 2nd operation command Y. When the 2nd operation command Y is '0', the state is an OFF-state and a velocity sensorless spectrum control inverter 2 does not supply power to a motor 3. If the 2nd operation command Y is 'l', the state is an ON-state and the velocity sensorless spectrum control inverter 2 supplies power to the motor 3. In the OFF-time limiter 4, an arithmetic process is carried out so as to have the 2nd operation command Y keep the OFF-state at least for the minimum OFF-time Δt. If the minimum OFF time Δt is selected to be longer than a time since the ON-state is turned to the OFF-state till the revolution of the motor 3 is reduced, the ON-state is not realized while the revolution of the motor 3 is not small. |
